Traditionally caused by consuming a diet mainly composed of corn and maize.
Severe deficiency leads to pellagra, which is characterised by dermatitis, dementia, diarrhoea, and eventually death.
Lean meat, poultry, fish, and peanuts are rich in vitamin B3 (niacin); milk and eggs are rich sources of tryptophan, the precursor of niacin.
Deficiency of vitamins B2 (riboflavin) and/or B6 (pyridoxine) reduces the synthesis of niacin from tryptophan and may lead to secondary vitamin B3 deficiency.
Rare in developed countries, although there are still outbreaks in Africa, India, and China, particularly in refugees and displaced people.
In developed countries, deficiency is most commonly associated with chronic alcohol use disorder, gastrointestinal malabsorption, and certain medications (e.g., isoniazid).
As the symptoms of mild vitamin B3 deficiency are similar to those of other B vitamin (e.g., B2 and B6) deficiencies that may coexist, the cause may be difficult to define.
Treatment with nicotinamide (niacinamide) will alleviate the cutaneous and many neurological symptoms within 48 hours.
Vitamin B3, also referred to as niacin, is the generic term for nicotinic acid, its amide (nicotinamide or niacinamide), and their biologically active derivatives. It is also found in the form of the pyridine nucleotide coenzymes nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADPH). These are essential in all cells for energy production, metabolism, and DNA repair. Severe deficiency results in pellagra, which is a combined deficiency of both niacin and its precursor, tryptophan. The symptoms of deficiency are primarily dermatitis, diarrhoea, and dementia. Death results if the condition is untreated.
History and exam
Key diagnostic factors
- presence of risk factors
- insomnia, depression, or memory loss
- intermittent stupor
- hallucinations or delirium
- peripheral neuropathy
- oppositional hypertonus or myoclonus
- cogwheel rigidity
- primitive reflexes
- nausea, vomiting, or diarrhoea
- glossitis, cheilitis, or stomatitis
Other diagnostic factors
- anxiety or paranoia
- anorexia, weight loss, or cachexia
- angular palpebritis
- chronic alcohol use disorder
- vitamin B2 (riboflavin) deficiency
- vitamin B6 (pyridoxine) deficiency
- eating disorders
- Hartnup's disease
- carcinoid syndrome
- antituberculous drugs
- Crohn's disease
- HIV infection
- copper deficiency
- certain drugs
- pregnancy and lactation
- age >65 years
- Alzheimer's dementia
- Parkinson's disease
1st investigations to order
- serum tryptophan
- urinary N-methylnicotinamide
- urinary N-methyl-2-pyridone-5-carboxamide
- urinary 2-pyridone/N-methylnicotinamide ratio
- skin biopsy
- photosensitivity testing
- serum albumin
- serum protein
Investigations to consider
- serum total iron
- iron-binding capacity
- transketolase activity
- thiamine pyrophosphate (TPP)
- riboflavin coefficient
- serum pyridoxal-5-phosphate
- serum cyanocobalamin
- serum folic acid
- red cell folic acid
- stool examination
- neutral aminoaciduria
- serum serotonin
- platelet serotonin
- urinary 5-hydroxyindoleacetic acid
- HIV antibodies
- mental-state examination
asymptomatic (marginal deficiency)
Whadi-ah Parker, PhD, RD(SA)
Senior Research Specialist
Centre for the Study of the Social and Environmental Determinants of Nutrition
Population Health, Health Systems and Innovation
WP declares that she has no competing interests.
Zandile J Mchiza, RD, PhD
School of Public Health
University of the Western Cape
ZJM declares that she has no competing interests.
Demetre Labadarios, MBChB, PhD, FACN
University of Limpopo
DL declares that he has no competing interests.
Dr Whadi-ah Parker, Dr Zandile J Mchiza, and Dr Demetre Labadarios would like to gratefully acknowledge Dr Nelia Patricia Steyn, a previous contributor, as well as Miss Nophiwe Job, Ms Nwabisa Tshefu, and Mr Machoene Derrick Sekgala for their contributions to this topic. NPS, NJ, NT, and MDS declare that they have no competing interests.
Alan Shenkin, MB, ChB, BSc, PhD, FRCP, FRCPath
Emeritus Professor of Clinical Chemistry
University of Liverpool
AS declares that he has no competing interests.
Alfredo Morabia, MD, PhD, MS
City University of New York
AM declares that he has no competing interests.
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